Devices and methods employing dual target auto exposure

Abstract

The method includes automatically adjusting a first control parameter in a device for capturing a first plurality of images, automatically adjusting a second control parameter in the device for capturing a second plurality of images such that automatic adjustment of the first control parameter is interspersed with, separate from, and obtained generally concurrently with the automatic adjustment of the second control parameter. The adjustment of the first control parameter being determined differently compared to adjustment of the second control parameter. The method may include attempting to decode a decodable indicia utilizing one or more images of the first and second plurality of images.

The invention claimed is: 
     
       1. A device for obtaining images comprising:
 an imaging subsystem for capturing images, the imaging subsystem comprising an image sensor; 
 wherein the device is configured for:
 generating a vertical synchronization signal having alternating active high periods and active low periods; 
 acquiring a first plurality of images based on a first control parameter; 
 adjusting the first control parameter for a first subsequent image of the first plurality of images based on a first prior image of the first plurality of images during an active high period of the vertical synchronization signal; 
 acquiring a second plurality of images based on a second control parameter that is different from the first control parameter; and 
 adjusting the second control parameter for a second subsequent image of the second plurality of images based on a second prior image of the second plurality of images during an active high period of the vertical synchronization signal; and 
 
 wherein the first control parameter for image N+2 is based on image N, and the second control parameter for image N+3 is based on image N+1. 
 
     
     
       2. The device of  claim 1 , wherein the device is configured for decoding an indicia in one or more images from the first plurality of images and/or the second plurality of images. 
     
     
       3. The device of  claim 1 , wherein:
 the first plurality of images and the second plurality of images are evenly interspersed. 
 
     
     
       4. The device of  claim 1 , wherein:
 the first control parameter and the second control parameter are the same control parameter; and 
 the first control parameter and the second control parameter have different values. 
 
     
     
       5. The device of  claim 1 , wherein:
 the first control parameter comprises a first exposure control parameter; and 
 the second control parameter comprises a second exposure control parameter. 
 
     
     
       6. The device of  claim 1 , wherein the device is configured for:
 adjusting the first control parameter according to a first algorithm; and 
 adjusting the second control parameter according to a second algorithm. 
 
     
     
       7. The device of  claim 1 , wherein the device is configured for:
 acquiring a third plurality of images based on a third control parameter that is different from the first control parameter and the second control parameter; and 
 adjusting the third control parameter for a third subsequent image of the third plurality of images based on a third prior image of the third plurality of images. 
 
     
     
       8. An indicia reader comprising:
 an illumination subsystem for projecting an illumination pattern; 
 an imaging subsystem for capturing images, the imaging subsystem comprising an image sensor; 
 wherein the indicia reader is configured for:
 generating a vertical synchronization signal having alternating active high periods and active low periods; 
 acquiring a first plurality of images; 
 while acquiring the first plurality of images, projecting the illumination pattern based on a first control parameter; 
 adjusting the first control parameter for a first subsequent image of the first plurality of images based on a first prior image of the first plurality of images during an active high period of the vertical synchronization signal; 
 acquiring a second plurality of images; 
 while acquiring the second plurality of images, not projecting the illumination pattern based on a second control parameter that is different from the first control parameter; and 
 adjusting the second control parameter for a second subsequent image of the second plurality of images based on a second prior image of the second plurality of images during an active high period of the vertical synchronization signal; and 
 
 wherein the first control parameter for image N+2 is based on image N, and the second control parameter for image N+3 is based on image N+1. 
 
     
     
       9. The indicia reader of  claim 8 , wherein:
 the first plurality of images and the second plurality of images are evenly interspersed. 
 
     
     
       10. The indicia reader of  claim 8 , wherein:
 the first control parameter and the second control parameter are the same control parameter; and 
 the first control parameter and the second control parameter have different values. 
 
     
     
       11. The indicia reader of  claim 8 , wherein:
 the first control parameter comprises a first exposure control parameter; and 
 the second control parameter comprises a second exposure control parameter. 
 
     
     
       12. A method for obtaining images comprising:
 generating a vertical synchronization signal having alternating active high periods and active low periods; 
 acquiring, with an imaging subsystem, a first plurality of images based on a first control parameter; 
 adjusting the first control parameter for a first subsequent image of the first plurality of images based on a first prior image of the first plurality of images during an active high period of the vertical synchronization signal; 
 acquiring, with the imaging subsystem, a second plurality of images based on a second control parameter that is different from the first control parameter; and 
 adjusting the second control parameter for a second subsequent image of the second plurality of images based on a second prior image of the second plurality of images during an active high period of the vertical synchronization signal; and 
 wherein the first control parameter for image N+2 is based on image N, and the second control parameter for image N+3 is based on image N+1. 
 
     
     
       13. The method of  claim 12 , comprising attempting to decode an indicia in one or more images from the first plurality of images and/or the second plurality of images. 
     
     
       14. The method of  claim 12 , comprising projecting an illumination pattern while acquiring the first plurality of images and/or the second plurality of images. 
     
     
       15. The method of  claim 12 , wherein the first plurality of images and the second plurality of images are evenly interspersed. 
     
     
       16. The method of  claim 12 , wherein:
 the first control parameter and the second control parameter are the same control parameter; and 
 the first control parameter and the second control parameter have different values. 
 
     
     
       17. The method of  claim 12 , wherein:
 the first control parameter comprises a first exposure control parameter; and 
 the second control parameter comprises a second exposure control parameter. 
 
     
     
       18. The method of  claim 12 , comprising:
 adjusting the first control parameter according to a first algorithm; and 
 adjusting the second control parameter according to a second algorithm. 
 
     
     
       19. The method of  claim 12 , comprising:
 acquiring a third plurality of images based on a third control parameter that is different from the first control parameter and the second control parameter; and 
 adjusting the third control parameter for a third subsequent image of the third plurality of images based on a third prior image of the third plurality of images.